Let An MIT Hurricane Expert Explain What All This Extreme Weather Means For The Planet

Climate change is perhaps the single most important challenge we'll deal with in the coming centuries. Kerry Emanuel breaks down what's happening now and how science can help us cope.

Kerry Emanuel is one of the world's foremost experts on hurricanes. As a respected scientist at the Massachusetts Institute of Technology, he's published a spate of important, widely cited papers linking climate change to increasingly dangerous weather. But for doing his job, Emanuel's also received emails threatening his family. He continues to do it anyway.

Yesterday, Emanuel hosted a timely Reddit AMA, during which he answered lots of questions about severe weather and climate change. Not everything can be definitively pinned on climate (even though this winter really sucks), nor can we point to one solution (like shooting aerosol into the atmosphere to cool it) to mitigate all the radical changes ahead. At the same time, Emanuel did illuminate critical ways in which science can help us frame our thinking for the future.

Not every single weather event can immediately be attributed to climate change. At the same time, we know that precipitation extremes are likely to increase (and might already have), heat waves will become more common, and "cold waves" less common, Emanuel says. Hurricanes also might become more intense.

One commenter asked if the next century will result in the end of civilization as we know it. In response, Emanuel says that the most probable outcome is one with "manageable" risks—though we aren't exempt from awful, outlier scenarios either.

The cold snaps many of us have been experiencing this winter are extreme only by the standards of the last decade or two.

"But as Marty Weitzman at Harvard has pointed out, we need to pay attention to the tail of the risk distribution, because the economic and societal risks can be very large there," Emanuel says. "Scientists by nature are conservative and do not like to talk about what might happen in the tail, but we do need to think carefully about tail risk as part of our overall assessment of the risk."

Translation: Even if civilization likely won't end, we still need to think about what could go extremely wrong.

While some disproportionately loud people like to point at the phenomenon of snow during winter, "cold snaps" don't really qualify as historically extreme.

"The cold snaps many of us have been experiencing this winter are extreme only by the standards of the last decade or two; in most places there were worse extremes further back in history," Emanuel says. "I myself have no idea how climate change might affect these, but my intuition (and, I bet, yours!) is that there will be fewer or less extreme cold snaps as the planet warms."

Remember that guy who dumped 100 tons of iron dust in the Pacific Ocean to try and increase carbon-sucking plankton blooms? That's an example of geo-engineering, processes by which we can try to mitigate climactic change by removing or storing atmospheric carbon. Some pretty radical geo-engineering schemes have been floated in recent years (like that alarming iron seeding scheme, for example, or injecting carbon dioxide underground for long term storage), but the risks of screwing them up are also rather large.

"Whether it is at all advisable, given the associated risks and known side-effects, is another question, and it is probably politically impossible," says Emanuel. "Also, there are strong risks, for example the acidification of the oceans owing to increases in dissolved CO2, that are not addressed by current geo-engineering proposals.

Some places will actually experience an improvement in climate, says Emanuel. Other regions, however, will be thrown wildly off-kilter. "But I do not think we are far enough along to be able to say just where things will be worst."

Scientific consensus overwhelmingly supports the evidence for man-made climate change, and we may be moving past the era where climate scientists receive death threats just for doing their work. "I think (and hope) that the worst of the threats, etc., are over for climate scientists, and you should not let such threats discourage you from engaging in the very vibrant curiosity-driven research in our field," Emanuel told one aspiring climate scientist.

When the effects of climate change seem so vast and unwieldy, what actions can we take now? Emanuel says we need to consider rising sea levels, which affects the magnitude of storm surges, and thus the damage caused by storms, as well as intense hurricane projections. "These considerations may, for example, enter into calculations of how high and how strongly we need to build sea walls in certain places," he says.

Unless we find an economical way to extract CO2 from the atmosphere, we are stuck with human-induced climate change.

Preaching doom isn't constructive. Neither is pointing to one solution and then going for a coffee break. "We have to intelligently weigh climate risks (and possible benefits) against the risks (and possible benefits) of any actions we might contemplate to deal with climate change," Emanuel says. "We have to get away from binary thinking... climate change will be either an apocalypse or nothing to worry about; solutions will either be a complete panacea or not work at all. I do think this is actually the way most people think about the problem of climate change. As usual, the extreme elements are the noisiest, though..."

One commenter asked what the world might look like if we ended all carbon dioxide emissions immediately. Emanuel wrote that "the concentrations of CO2 would fall of[f] at first fairly rapidly (tens of years) but then much more slowly, taking a thousand years or more to return to pre-industrial levels." Unfortunately, that scenario's unlikely. "So unless we find an economical way to extract CO2 from the atmosphere, we are stuck with human-induced climate change for a long time," Emanuel says.

Last, but not least, being a hurricane expert does have its perks. On flying into a hurricane: "Everyone should experience a flight into the eye of a hurricane," Emanuel writes. "Spectacular views, and not as much turbulence as on many commercial flights..."

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"The cold snaps many of us have been experiencing this winter are extreme only by the standards of the last decade or two; in most places there were worse extremes further back in history,"

I think the point is not the extreme temperature but the intrusion of the polar vortex into lower latitudes and warmer air masses penetrating into the polar regions - accelerating thawing. Are you suggesting these kind of jet stream anomalies are part of extreme cold snaps in general?